How is the brain wired?

Published: Autumn 2011

How the brain works remains largely a mystery. But physicists at Notre Dame’s Interdisciplinary Center for Network Science and Applications (iCeNSA), working with neuroscientists in France, have recently shed some new light on the process.

Understanding how the brain works on a neuronal level would be almost impossible, ND physics Professor Zoltan Toroczkai notes. “You’d get lost in the detail. It would be like looking at a blueprint of the tens of millions of transistors in the integrated circuits of an iPhone or laptop.”

Therefore the ND researchers, who study networks of all types, from Facebook to disease spread, took what is called a “top-down approach” to their analysis.

Specifically, Toroczkai and post-doctoral associate Maria Ercsey-Ravasz found that the cortex of the primate brain is organized into a weighted network of functional areas. Analyzing a massive amount of data on macaque brains collected by the French scientists, the ND researchers found that brain network connections are greatest between areas that are closest to each other, trailing off in a consistent pattern related to distance.

Just how complicated brain circuitry is can be illustrated by the fact that the adult primate brain contains an estimated100 billion neurons connected at more than 100 trillion points. All these connections are organized into bundles running between the 83 functional areas in the macaque brain and more than 120 areas in the human brain.

“The brain seems to work very differently than a computer,” Toroczkai notes. “Although it has not been proven, it seems to employ a vastly different computing paradigm than the zeros and ones that today’s digital machines use.”

The ultimate goal of the iCeNSA researchers is to understand that new paradigm as well as how sense information is converted into electrical signals and then processed in the brain.